This invention relates to a battery voltage detecting circuit and apparatus for an electronic timepiece which detects the voltage.
The electric timepiece using a battery has the defect wherein the battery must be exchanged for new battery before the lifetime of the battery has ended.
More particularly, at the present, the wearer forgets often the time for exchanging the battery since the lifetime of the battery for an electronic timepiece is extended by the improvement of the electronic timepiece circuit and the battery structure of the electronic timepiece. Therefore, it has been proposed that the electronic timepiece in which the battery voltage detecting apparatus is incorporated, generate in the alarm just before the end of the lifetime of the battery.
Most electronic timepieces detect with analogue comparison the condition when the battery voltage level lowers below a setting voltage level which is determined by a resistance element and a semiconductor. However, the desired setting voltage cannot be obtained is not able to if the variation of the semiconductor-characteristic is not compensated.
Therefore, the conventional battery voltage detecting apparatus has the disadvantage that the variation of the semiconductor-characteristic has to be compensated and the adjusting work has to be made to individual electronic timepieces.